Abrasive disc for a multiple disc grinding machine, in particular for processing stone and like materials, and a grinding machine including said disc

ABSTRACT

An abrasive disc for a multiple disc grinding machine is described, including a disc-shaped support having a circumferential rim on which the abrasive material is placed and an opposing central hole for fitting on to a driving shaft of the grinding machine, said hole extending through the thickness of the disc-shaped support, in which a portion of said central hole has a diameter greater than the diameter of the connection to said shaft, such that an annular chamber is formed in the thickness of the support. The further disc includes at least one radial recess formed on a front surface of the disc-shaped support and extending from said annular chamber towards the circumferential rim of said disc, in such a way that a coolant fluid fed into the driving shaft can accumulate in said annular chamber and can then flow through said radial recess towards the abrasive edge of said disc.

TECHNICAL FILED

The present invention relates to an abrasive disc for a multiple disc grinding machine having the features set out in the preamble of the main claim. The invention also relates to a multiple disc grinding machine including a plurality of discs of the above-mentioned type.

TECHNOLOGICAL BACKGROUND

The invention is for use in particular in the sector of the processing of stone and like materials, in which use is made of multiple disc grinding machines having a plurality of cutting discs with abrasive segments combined in a pack on a shaft which may be caused to rotate. When using multiple disc grinding machines of the above-mentioned type, use is typically made of coolant fluids which are conveyed to the processing zones to ensure that the heat generated by processing, following contact between the abrasive sectors and the surfaces of the workpiece, is adequately dissipated. In known solutions the shaft is provided with an internal hole in order to convey the fluid to a distributor member, for instance a bushing interposed between the shaft and the discs and designed to collect the fluid and distribute it to the exterior of the discs in the processing zones. This solution nevertheless requires the provision of a specific distributor member which has to be mounted when the cutting discs are being mounted on the multiple disc grinding machine.

DESCRIPTION OF THE INVENTION

A main object of the invention is to provide an abrasive disc for multiple disc grinding machines designed to provide a coolant distribution system which is structurally simpler and easier to use, but which continues to provide efficient cooling of the tool.

This object is achieved by the invention by means of an abrasive disc for a multiple disc grinding machine embodied in accordance with the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features of the present invention will become clear from the following detailed description of a preferred embodiment thereof which is given with reference to the appended drawings which are provided purely by way of non-limiting example and in which:

FIG. 1 is a perspective view of an abrasive disc for a multiple disc grinding machine according to the invention;

FIG. 2 is a view in axial section of the disc of FIG. 1;

FIG. 3 is a view in partial section of a multiple disc grinding machine equipped with abrasive discs according to the invention.

PREFERRED EMBODIMENTS OF THE INVENTION

With reference to the appended drawings, an abrasive disc for a multiple disc grinding machine embodied in accordance with the present invention is shown overall by 1. A grinding machine equipped with a plurality of abrasive discs closed in a pack on a driving shaft 3 of the grinding machine which may be caused to rotate about an axis X is shown by 2. Only the cutting disc 1 will be described in detail below, as the features described mirror those of the remaining discs of the pack mounted on the shaft 3.

The multiple disc grinding machine designed in this way is for particular use for the processing of stone and like materials but could be used in other fields, for instance for the processing of ceramics, refractory materials or glass.

The disc 1 comprises a disc-shaped support is which is axially symmetrical with a main axis shown by Y in the drawings and bears a circumferential rim 4 on which abrasive cutting sectors 5 are applied.

The transverse thickness of the disc at its central portion, measured parallel to the axis Y, is shown by 6.

The support is is also provided with a central hole 7 for connection to an end portion 3 a of the driving shaft 3 which causes the disc to rotate during cutting operations involving tangential contact between the rim 4 and the material to be processed.

The connection hole 7 has a first cylindrical through section 7 a which comes into coupling contact with the driving shaft 3 and a second cylindrical through section 7 b extending as an axial continuation of the first section, this second section having a diameter greater than the first section. As a result of this feature, an annular chamber shown by 8 is formed at the location of the second through section 7 b, following connection with the shaft 3, whose function will be explained in detail in the following description. The sequence of through holes 7 a, 7 b extends through the entire transverse thickness 6 of the disc, so that the section 7 b extends, with its free end, up to the location of a front transverse surface of the disc shown by 9. This surface extends with an annular configuration from the hole 7 in the direction of the rim 4 over a predetermined radial development. When the discs are mounted as a pack on the shaft 3, the surface 9 of each disc abuts against the adjacent disc and as a result of the axial clamping action of the pack of discs, this surface acts as a friction member designed to prevent the relative sliding of adjacent discs.

The front surface 9 is provided with at least one radial recess, shown by 10, which extends from the annular chamber 8 in the direction of the rim 4 radially including the whole surface. A preferred choice, shown in the appended drawings, is to provide three recesses 10 angularly spaced from one another at regular intervals (with an angular pitch of 120°), although the invention could function with other configurations. The recesses 10 may also be readily provided on the front surface 9 by respective radial milling operations on the surface 9. As is clearly shown in FIG. 3, once the discs are positioned as a pack on the shaft 3, the annular chamber 8 is connected in fluid communication with each of the recesses 10 so as to ensure a passage for a coolant fluid accumulated in the chamber and conveyed to the exterior of the disc via the recess 10.

The driving shaft of the grinding machine 2 is provided with an internal axial duct 11 for supplying the coolant fluid, which duct is continued by one or a plurality of radial end ducts 12 opening at the location of cylindrical shell of the end portion of the shaft 3 designed to house the abrasive discs.

It is advantageous for the thickness 6 of the disc 1 in contact with the shaft to be smaller than the diameter of the hole 12 provided on the shaft, so as to ensure a passage for the coolant fluid from the chamber 8 containing the fluid to the recesses 10, which recesses 10 therefore form a kind of channel for supplying the fluid to the exterior of the disc in order to distribute the fluid to the processing zones close to the abrasive sectors of the circumferential rim 4.

The provision of the annular chamber 8 in fluid connection with the recesses 10 therefore makes it possible for the coolant fluid to be accumulated in the chamber and then to flow radially, under the centrifugal effect of the rotation of the grinding machine, along the recesses so as efficiently to reach the processing zone of the abrasive sectors of the discs and thus to ensure the cooling of the surfaces in relative contact of the discs and the material being processed.

In a variant of the invention the cylindrical shell of the driving shaft 3 intended to receive the cutting discs, may be provided with a groove 13 (or a plurality of grooves 13) extending axially along the whole pack of discs and in fluid communication with the supply holes 12 of the coolant fluid. This groove may improve the distribution effect of the coolant fluid to each annular chamber of the discs mounted in a pack on the shaft, as shown in FIG. 3, in the lower axial section of the grinding machine.

The invention thus achieves the objects set out above and provides many advantages over known solutions.

A main advantage lies in the simpler structure and operation of the cooling system which the invention applies to multiple disc cooling systems, avoiding the use of specific distribution members for the coolant fluid, such as the bushings or like distributors for which known solutions make provision. This simpler structure is advantageously reflected by easier use, especially as regards operations to mount the pack of discs on the grinding machine and remove it therefrom, a major advantage when taking account of the fact that these tools have to be readily and rapidly interchangeable as a result of the wear of the abrasive profiles to which they are subject when processing materials. 

1. An abrasive disc for a multiple disc grinding machine, the abrasive disc comprising: a disc-shaped support (1 a) having a circumferential rim (4) on which an abrasive material is disposed to form an abrasive outer edge of the abrasive disc and a central hole (7) for fitting on to a driving shaft (3) of the grinding machine, said hole (7) extending through an axial thickness of the disc-shaped support (1 a), wherein a portion of said central hole (7) has a diameter greater than the diameter of the shaft (3) to which the abrasive disc is adapted to be connected, such that an annular chamber (8) is formed in the thickness of the support, at least a front surface of the disc-shaped support (1 a) having at least one radial recess (10) formed therein the at least one radial recess extending from said annular chamber (8) towards the circumferential rim (4) of said disc, in such a way that a coolant fluid fed into the driving shaft (3) can accumulate in said annular chamber (8) of the disc shaped support and can then flow through said radial recess (10) towards the abrasive edge of said disc; and wherein the front surface of the disc-shaped support includes at least one axially projecting portion which defines the axial thickness of the disc-shaped support and extends a radial distance away from the hole, the at least one axially projecting portion having an axially-facing abutment surface thereon, the abutment surface being adapted to abut a next adjacent disc when a plurality of said abrasive discs are combined in a pack, the abutment surface forming a friction member which prevents relative circumferential sliding of said abrasive disc relative to said next adjacent disc.
 2. The disc according to claim 1, in which three radial recesses (10) are provided on said front surface (9), the recesses being spaced apart angularly at regular intervals.
 3. The disc according to claim 1, in which said portion of the central hole (7) forming said annular chamber (8) extends as a continuation of a portion of the hole (7) intended to contact the driving shaft (3) of the grinding machine when the disc is connected to it.
 4. A multiple disc grinding machine comprising a driving shaft (3) receiving thereon a plurality of abrasive discs (1) combined in a pack on said shaft (3), each of said discs being defined in claim
 1. 5. The multiple disc grinding machine according to claim 4, in which said driving shaft (3) comprises at least one hole (17) for the feed of coolant fluid, the hole extending radially in the end portion of said shaft (3) which is intended to receive the plurality of cutting discs (1), and opening on a cylindrical shell which comes into contact with the discs, in which a transverse thickness of the discs is smaller than a diameter of said at least one coolant fluid feed hole (12) in the shaft, so as to permit the passage of fluid from said feed hole (12) to the annular chamber of the corresponding disc and thence to the corresponding recess (10).
 6. The multiple disc grinding machine according to claim 5, further comprising at least one channel (13) extending axially in the cylindrical shell of the end of the driving shaft intended to be connected to said discs, said channel (13) communicating with said radial hole (12) for the feed of the coolant fluid and being capable of bringing said hole (12) into communication with the annular chambers (8) of the corresponding discs (1) which are fixed in a pack on the driving shaft (3).
 7. The multiple disc grinding machine as defined in claim 4, wherein a surface of each of said abrasive discs in said pack abuts against a corresponding surface of the adjacent abrasive disc, and wherein axial clamping action of the pack of the abrasive discs causes said surfaces to act as friction members which prevent relative sliding of adjacent ones of the abrasive discs.
 8. The abrasive disc as defined in claim 1, wherein the central hole is defined in the disc-shaped support by a first cylindrical surface which comes into coupling contact with the driving shaft and a second cylindrical surface which axially extends from the first cylindrical surface and is radially outward therefrom, the second cylindrical surface being said portion of the central hole having the diameter greater than that of the shaft and thus of the first cylindrical surface, such that the first cylindrical surface couples the abrasive disc to the driving shaft with a continuous coupling contact and the second cylindrical surface defines said continuous annular chamber which extends about the circumference of the abrasive disc and through which fluid flows into said radial recesses.
 9. A plurality of abrasive discs for a multiple disc grinding machine, the plurality of abrasive discs being combined in an axially-stacked pack adapted to be received on a driving shaft of the multiple disc grinding machine, each of said plurality of abrasive discs being as defined in claim
 1. 10. A multiple disc grinding machine comprising: a driving shaft; a plurality of abrasive discs combined in a pack on said shaft, each of said discs comprising a disc-shaped support having a circumferential rim on which an abrasive material is placed and an opposing central hole for fitting on to a driving shaft of the grinding machine, said hole extending through the thickness of the disc-shaped support; and wherein a portion of said central hole has a diameter greater than the diameter of the connection to said shaft, such that an annular chamber is formed in the thickness of the support, and wherein at least one radial recess is formed on a front surface of the disc-shaped support and extends from said annular chamber towards the circumferential rim of said disc, in such a way that a coolant fluid fed into the driving shaft can accumulate in said annular chamber and can then flow through said radial recess towards the abrasive edge of said disc; and wherein the driving shaft includes at least one hole for feeding coolant fluid, the hole extending radially in the end portion of said shaft which is intended to receive the plurality of cutting discs, and opening on a cylindrical shell which comes into contact with the discs, in which the transverse thickness of the discs is smaller than the diameter of said at least one hole for the feed of coolant fluid in the shaft, so as to permit the passage of fluid from said feed hole to the annular chamber of the corresponding disc and thence to the corresponding recess.
 11. The multiple disc grinding machine as defined in claim 10, wherein the driving shaft includes at least one channel extending axially in the cylindrical shell of the end of the driving shaft intended to be connected to said discs, said channel communicating with said radial hole for the feed of the coolant fluid and being capable of bringing said hole into communication with the annular chambers of the corresponding discs which are fixed in a pack on the driving shaft.
 12. The multiple disc grinding machine as defined in claim 6, wherein a surface of each of said abrasive discs in said pack abuts against a corresponding surface of the adjacent abrasive disc, and wherein axial clamping action of the pack of the abrasive discs causes said surfaces to act as friction members which prevent relative sliding of adjacent ones of the abrasive discs.
 13. A multiple disc grinding machine comprising: a driving shaft; a plurality of abrasive discs combined in a pack on said shaft, each of said discs comprising a disc-shaped support having a circumferential rim on which an abrasive material is placed and an opposing central hole for fitting on to a driving shaft of the grinding machine, said central hole extending through the thickness of the disc-shaped support; wherein a portion of said central hole has a diameter greater than the diameter of the connection to said shaft, such that an annular chamber is formed in the thickness of the support, and wherein at least one radial recess is formed on a front surface of the disc-shaped support and extends from said annular chamber towards the circumferential rim of said disc, in such a way that a coolant fluid fed into the driving shaft can accumulate in said annular chamber and can then flow through said radial recess towards the abrasive edge of said disc; and wherein a surface of each of said abrasive discs in said pack abuts against a corresponding surface of the adjacent abrasive disc, and wherein axial clamping action of the pack of the abrasive discs causes said surfaces to act as friction members which prevent relative sliding of adjacent ones of the abrasive discs; and wherein the driving shaft includes at least one channel extending axially in the cylindrical shell of the end of the driving shaft intended to be connected to said discs, said channel communicating with said central hole for the feed of the coolant fluid and being in communication with the annular chambers of the corresponding discs which are fixed in a pack on the driving shaft.
 14. The multiple disc grinding machine as defined in claim 13, wherein the driving shaft includes at least one supply hole for feeding coolant fluid, the supply hole extending radially in the end portion of said shaft which is intended to receive the plurality of cutting discs and opening on a cylindrical shell which comes into contact with the discs, in which the transverse thickness of the discs is smaller than the diameter of said at least one supply hole for the feed of coolant fluid in the shaft, so as to permit the passage of fluid from said supply hole to the annular chamber of the corresponding disc and thence to the corresponding recess.
 15. The multiple disc grinding machine as defined in claim 4, wherein the central hole is defined in the disc-shaped support by a first cylindrical surface which comes into coupling contact with the driving shaft and a second cylindrical surface which axially extends from the first cylindrical surface, the second cylindrical surface being said portion of the central hole having the diameter greater than that of the shaft and thus of the first cylindrical surface, such that the first cylindrical surface couples the abrasive disc to the driving shaft with a continuous coupling contact and the second cylindrical surface defines said continuous annular chamber which extends about the circumference of the abrasive disc and through which fluid flows into said radial recesses. 